Vehicle On-Board Diagnostics (OBD) System Check

This should be the starting point of any driveability or symptom diagnosis. Perform the vehicle on-board diagnostic (OBD) system check as defined in the Body/Electrical. This check verifies the integrity of the powertrain control module (ECM) and its self-diagnostic capabilities. If diagnostic trouble codes (DTCs) are stored, go directly to the numbered DTC chart.